1. Field of the Invention
The present invention relates to data processing systems, and more particularly to the adaptation of an acoustic bar typewriter for use as a data processing printer.
2. Description of the Prior Art
In the recent past the SCM Corporation has put forth on the market a typewriter sold under the trademark "Typetronic," which includes an acoustic bar against which the typewriter keys are struck. The acoustic wave generated by each key strike then propagates to the two ends of the bar and is compared thereat both for the time of arrival and for its phase. The arrival differences and phase are then utilized to determine the position of the keys making the strike and can therefore be converted to the control signals for the print cycle.
The advantages of the foregoing typewriter are manyfold. Of primary advantage is the result that very elaborate mechanical and electrical arrangements for each key are avoided. There is, however, a disadvantage in that the resulting electrical signals are real time based and are not conveniently adapted to the computer character code used in the art. For example, it is the common practice in the art to use ASCII or similar binary code for alphabetic character encoding commonly designated either as the IEEE488 or the RS232 encoding scheme. These coding schemes, being referenced to the cycle rate of a data processing device, do not conveniently provide the necessary time apertures for controlling the SCM Typetronic typewriter.
It is therefore the intent of the present invention to provide an interface through which the conventional or commonly practiced codes are converted to a signal sequence simulating the acoustic signal propagation through the acoustic bar.